The King turned up to the COP28 climate summit on Friday wearing a tie depicting the Greek flag, in a move which some people think could be a dig at the prime minister.
Charles was at the summit giving a speech urging world leaders to take more action on climate change, warning the dangers of global warming were no longer a distant risk.
"I pray with all my heart that COP28 will be another critical turning point towards genuine transformational action," he said, referring to the 2015 summit held in France.
@bbclaurak There u are
However, for some people, his choice of tie was the centre of attention, following a political row over who should keep the Elgin marbles, known in Greece as the Parthenon sculptures.
Rishi Sunak cancelled a meeting with his Greek counterpart Kyriakos Mitsotakis over the historic marbles, which were removed from Greece to Britain by people working for Thomas Bruce, 7th Earl of Elgin, in the early 1800s.
They are now held in the British Museum, but the Greek government has demanded that Britain give the sculptures, which date back to antiquity, back to their original owners.
King Charles’s tie could have been a nod to the controversy. His father, Prince Philip, had Greek roots, so he may well feel strongly about the matter.
People on social media were quick to jump on the apparent statement by Charles. One person joked: “F for effort. If he wanted to make a statement he should have worn a toga.”
Another said: “Is the King going to return everything his family have stolen?”
And a third added: “My approval rating for King Charles has just gone up. A lot.”